[Wien] bulk and surface DOS's discrepancy

[morteza rafiee]

Dear Wien users.
  I have created a surface with several layers. The number of our layers is comparable with the number of layers used by others. We except that the physical properties of our middle layers are similar to the bulk properties. Hence we expect to obtain similar electronic structures for both the middle layers and bulk within our calculations. To keep the same accuracy the density of k-points in the bulk and surface calculations were taken to be equal. We have not yet relaxed the atoms in the surface. We have compared the total density of states (DOS’s) of a selected atom in the bulk with the similar atom in the middle layer. The comparison shows that they are not exactly compatible with each other. For instance the DOS of the bulk shows insulator behavior. This is in the case that the DOS of the atom in the middle layer shows a metallic behavior. We have observed that the metallic behavior approaches to the insulator behavior by increasing the number of layers. However,
 neither our facility does allow us increasing the number of layers more than this (10-pair-layers=20 layers) nor the calculations of the others suggest such an increasing towards such extremely heavy calculations. I do not know if the relaxation of the layers will fix the problem or not. We also not aware whether this is a usual problem in surface calculations or we must try to reach exactly the bulk DOS.
  I will be thankful to every body who help me.
  Your.
  Morteza Rafiee.
   
   
   

 
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